The invention relates to a vertical axis wind turbine with an annular array of stator vanes to direct wind into the rotor, where each vane has an outer edge flange to create a turbulent swirling boundary layer adjacent to the vane surfaces that rotates in a direction that draws and redirects air flow into the air flow channels defined by the stator vanes.
Wind is used as a source of energy for driving horizontal axis and vertical axis windmills. Horizontal axis windmills have been used extensively to drive electrical generators however they suffer from several disadvantages, including danger to birds and air traffic, obscuring the landscape with banks of rotating windmills, and in the case of large diameter horizontal axis propellers, supersonic speeds at the tips of the rotors.
Vertical axis wind turbines have been provided in the prior art with a central rotor surrounded by stationary ring of vanes that serve to direct and compress air from the wind before is directed at the rotor blades. A disadvantage of a horizontal axis windmill is that it must turn to face the wind direction whereas the exposure of a vertical axis windmill or turbine wind remains constant regardless of the wind direction.
example of vertical axis wind turbine is shown in U.S. Pat. No. 5,391,926 to Staley et al. that uses double curved stator blades to direct wind current to the rotor assembly and to increase structure stability of the thin stator blades.
Further example of a vertical axis rotor within a ring
blades is shown in U.S. Pat. No. 5,852,331 to Giorgini. In this case, the stator blades are disposed in a helical pattern however significant shielding of the airflow is anticipated reducing the energy captured by this type of stator arrangement.
U.S. Pat. No. 6,015,258 to Taylor discloses another wind turbine that includes a ring of stator blades of an airfoil shape to reduce impedance of air directed towards the central rotor assembly.
Further, U.S. Patent Application Publication No. US2002/0047276 A1 discloses an outer ring of planar stator blades to direct flow of wind into a central rotor assembly.
A disadvantage of all the vertical axis windmills of the prior art relates to the inability to capture wind from the entire exposed surface of the stator assembly. The disposition of the stators themselves shield a portion of the exposed surface of the stator from the wind and directing the wind to the central rotor assembly. In general, the exterior of the stator is usually cylindrical
Ideally, the entire one half cylindrical surface that is exposed to wind should be able to capture wind and direct wind into a swirling flow of partially compressed air towards the central rotor assembly. Unfortunately, in most cases the prior art enables capture of only a portion of the entire semi-cylindrical surface area thereby requiring larger turbine units to capture more energy from the wind exposure.
It is an object of the present invention to provide a vertical axis wind turbine which enables capture of wind energy from a larger portion of the exposed surface of the stator assembly relative to the prior art.
It is a further object of the invention to provide a stator assembly which is structurally reinforced.
It is further object of the invention to provide a stator assembly which is simply constructed of inexpensive material.
Further objects of the invention will be apparent from review of the disclosure, drawings and description of the invention below.
The invention provides a vertical axis wind turbine with a turbine rotor with rotor blades disposed for rotation about a substantially vertical axis. The turbine includes multiple vertically extending stator vanes circumferentially spaced apart about the rotor in an annular array. Each vane has a radially inward facing surface, a radially outward facing surface and a flange on an outer edge of each vane. The flange serves to create a turbulent swirling boundary layer on the vane surfaces that rotates in a direction that draws and redirects air flow into the air flow channels defined by the stator vanes that is then compressed by the narrowing of the channels and directed to the rotor blades to drive the turbine.